Two-stage alkylation with olefin streams containing propylene and ethylene



y l948- c. o. BAKER TWQ-STAGE ALKYLATION WITH OLEFIN STREAMS CONTAINING PROPYLENE AND ETHYLENE Filed April 19, 1946 kUQQQQQ Mk 1 wxxsq QR INVENTOR. Bufmlab 5 M AGE/VT EENQQ Char/e: OV/D fiaker R R3 R30 RN &

columns. Any suitable type of absorption appae ratus may be employed for the first column, such as a packed column or a bubble plate column. 7

For the second column, an absorber of the bubble plate type is preferred because longer contact times are desirably employed for absorption alkylation of ethylene, and these contact times can be more readily attained when using a bubble plate column. By suitable control of the contact time in the second absorption-alkylation column, the ethylene alkylation reaction may be substantially complete by the time the absorbed ethylene and isoparaffin-catalyst solution leaves the column.

tween the plates, for example. Where sufiicient time for complete reaction is not obtained, a small? dation products of the catalyst should be of' a fluid or soluble nature, so that they will be carried out of the absorption reactors with the rich absorption menstruum-alkylate mixtures. Aluminum bromideis a suitable catalyst, having considerable solubility in light paraffin hydro-; carbons at normal and moderately elevated temperatures. Additionally, the hydrocarbon complex'tar that is slowly formed by side reactions in the alkylation steps is of a light fluid nature and will be largely carried out of the absorptionreactors with the liquid eflluents from which it may be removed by gravity settling for recovery and regeneration.

Sufiicient time for complete reaction may be obtained by the use of time tanks be-;-

product. I -reacts, and the remainder 'passesras overhead,

fromthe absorber ll through line l as a conflowing stream of isobutaneiwhereby the propylene under the reaction conditions maintained is converted substantially entirely to "alkylate Only a small portion of the ethylene stituent of the lean gas,1which now contains, in

additionito the ethylene, a relatively minor proportionoi unreacted propylene'and substantially allof the methane and hydrogen and substantial portions of the ethane and propane contained in the;original stream. 7 V

Richdiquid 'eflluent leaves the absorber H K through line it and contains excess isobutane absorbent, isobutane-propylene alkylate, some isobutane-ethylene alkylate, some absorbed but 1 unreacted ethylene, traces of unreacted propylme; and some propane, ethane, andmethane.

This efiluent in line i 6 is sent to a flash evaporator l! where the light. gases and most'of the. iso-.. butane and alkylate are taken on: asloverhead' through line ill. The bottoms from the evapora- I tor ll, consisting of'a concentrated solution of the aluminum bromide catalyst in the unvaporized isobutane-alkylate liquid, are taken off .through line '29 and passed to gravity settler 21.. I

Tar is removed through line 22,.and the alumi-i num bromide concentrate solution is passed through'line 2d to line I l {for admixture with isobutane and reuse in tower H. The relatively small amount of alkylateploduct contained in the recycled aluminumbromide concentrate solu-'- My invention'may be. best understood by refer- 7 ence to the drawing wherein the essential steps in one mode of operation are diagrammatically illustrated. A gas stream. containing ethylene and propylene in admixture with light paraffins, as methane, ethane, and propane, and hydrogen is introduced through line It into the base of absorber ll packed with asuitable packing material 12, such as Raschig rings. An isobutane solutionof aluminum bromide containing minor amounts of alkylate, productand heavier saturated hydrocarbons obtained in a manner hereinafterdescribed, is introduced into the top of the absorber through line I4. The 'alkylation-absorption reactionis exothermic and, to maintain the desired temperature in tower H, the tower may be provided with suitable cooling-means (not shown), suchas cooling coils, etc.

tio of. isoparaflin to propylene, and contact time oi liquid pertheoreticalequilibrium contact space are maintained in absorber II in order to obtain maximum conversion of propylene and minimum conversion of ethylene'.contained in the gas, stream. Suitable conditions are: catalyst con- 7 I Condi-' tions of catalyst concentration, temperature, ra-

centration--1.2%' by iweightof isobutane; 'tem-,

perature'60 F.; pressurep. s. i. a.; con

"tact time of liquid per theoretical equilibrium contact space of absorber-82 seconds; mol ratio propylene dissolved thereinof isobutane to eatery The gas ascends upwardly'through the column counter-currently; contacting the downwardly maintained without feedingexcessive volumes of isobutane to the tower llffrom -fe ed. lin'ei l l in the tower;

tion has no material effect on; the absorptionalkylationreaction. 1 V 7 The overhead from theevaporator in 1inel9is then sent to arsuitable fractionating column 26 for separation of the light gases which, are discharged through line 21. The isobutane is s'epf arated from the propylene-isobutane alkylate; product in fractionator 23 and recycled after condensation (not shown) to line Mvia line 25. The

alkylate product is drawn ofi'from the fractionator 29 through line. 30 for final stabilization and treatment;

The overhead gas from'absorber ll passing through line l5 contains, in addition to unreacted ethylene, a portion of unreacted propylene, and

the remaining light parafiinic constituents of the original gas stream, a portion of isobutane which has been vaporized from the downflowing stream.

of liquid isobutane absorbent. Toreduce the volume of gasbein handled in the second tower.

3|, as well as to assist in control of temperature in tower I], the overhead gas in line .l5-is cooled e in condenser 32 to a temperature such that the greater portion of the isobutane is condensed to the liquid state and is then passed through line 34 to receiver 35 from which the condensed .iso-

butane is removed through line 36 and pumped l by means of pump 37 to distributing line 39. From distributing line 39, the condensed isobutane 'is passed through a plurality of lines indicated by lines 40, 4|,42, and 44 to a plurality of pointsin the tower l I. By means of this system of distribr uting the. condensed isobutane to 'a' plurality of points in the tower l|,.no1; only i temperature control assisted, but, in addition, the desired ratio of isobutane to propylene dissolved therefin isorder to compensate for evaporation of; isobutane as the liquid stream descends through the tower and as assurance that the proper isobutane-pro! V maintained at the bottoinof} pylene ratio will be h r maiuineipor ion of th erhead g s. n ver??? is emo cdthrcugh lin nd pump d by means of ctinripressor 46 to tower 3|. Tower 3| ill usu l v-be era ed a a hi p ssu thantower ,llpand, to remove therheat ofcome pression from the. incoming gas, cooler 41 is provided mime- 45. Tower 3! is of the bubble plate type modified-to the extent that each plate is provided witl 1 ;a time tank to obtain Sufiiciently long time. of contact of dissolved gas and liquid isobutane absorbent for effective absorptioneale kylation. Liquid isobutane absorbent containing dissolvedaluminum bromide. enters the top of the tower ,through. lin '49 .and passes downwardly through-the. tower. accumulating on the plates i1- lustratedbyplate 50. The ascending: gas passes through bubble caps 5 I to obtain intimate contact of gas and liquid. The accumulated liquid on eacl' -plate, passes to a time-tank, illustrated by time.tank-52,- through line.54 provided with pump 55 and, aftersultable residence time in the tank, is returned tothetowerthrough line 56 to flow to the next successively lower plate. To maintain proper-temperature control in the tower 3|, the liquid lnthe timetanks may be cooled by providingsuitable.cooling means (not shown) such as a Qoolerwithin the tanks or by circulating theliquidwithin the tank through an externalcooler.

Reaction conditions within ,the tower .3I are maintained suitable for alkylation of the isobutane with the ethylene. A small amount of propylenewill. alsobe contained in the ascending gas and, because of thegreater alkylatingactivity of thepropylene, will alkylatethe isobutane under the, conditionsfavorable for reaction with the ethylene. Suitablealkylating conditions in tower 3| are: aluminum bromideconcentration in the isobutane-.3,0 weight per cent; temperature- 130 .F.; .pressure=-265..p. s. i. a.; residence time of liquid per equilibrium contact spa'ce.30 minutes.

The rich liquid .eflluent leaves tower 3| through line 51 and contains excess isobutane absorbent, isobutane-ethylene. allsylate consisting essentially of 2,3.Idimethyl'butane, small amount of isobutanerpropylene alkylate,..some absorbed but unreacted ethylene and perhapstraces of propylene, and sqme ropane, ethane, and methane, The eflluent is treated in similar manner to .theefiluent from tower l i .bypassingto flash. evaporator @59. The light gases are taken overhead through line 60, while the bottoms containing the alumim bromide and any tar. form d durin th r on Pa s to ravity settlerfi I, The tar is with! drawnffrom the settler through line 62, and the aluminum bromide concentrate is taken overhead through line 64 and recycled to line 49 for admixture with isobutane and reuse in tower 3|. The overhead. from evaporator 59in line 60 is sent to a suitable fractionation columnfii for separation of the light gases which discharge through line 66. .The isobutane is separated from the alkylate product in iractionator 61 and recycled after condensation (not shown) through line I4. The alkylate product is drawnoif from the fractionator 61 through line for final stabilization and treatment.

The overhead isobutane from'fractionators 29 and El'admixeswitn fresh liquid isobutane entering the-systemthrough line 1 land passes through line lltotowers ll'and 3| The aluminum bro-' mide concentrate!fromsettlers Zl and BI adi-nixes 'withctheaisohutane entering towers" II and 3| respectively, but additional aluminum bromide l September 24, 1945.

u ual yheaadeedi he eto dbrins th concentrati ns to the des r d v luefor reach tower.

Suitablfi adju tm ntf. the alumi m bromide e tra n of h isobutane e termg: towermay be effected byadding "a concentrated solo tion of aluminum. bromide in isobutane from reservoir H to the isobutane stream in line 49. In similar manner the aluminum bromide concentration of the isobutane solution entering tower I I may beadjusted by passing aluminum bromide concentrate from reservoir 12- to line I4.

The overhead gases from'the tower 3| pass through line 74 and will contain an appreciable portion of the isobutane absorption menstruum. This gas streamis then sent to a third absorption tower 15 wherein the gas is contacted with a conventional light absorption oil having a molecular weight considerably in "excess, of that of the isobutane, say from-160 toj240,'intro'duced through'line-lfi; Absorption-tower 15 maybe of the conventional bubble-plate type wherein'the downcoming oilfcol-lectson the successive-plates H and then flows through the respective downcomers 19' to the-next succeeding plate while the ascendinggas rises through the bubble caps on each successive plate. The gas overhead, free of isobutane, leaves tower 15 through line 81 and is suitable for use as a, fue1 gas; The rich absorption 0..il bottoms in line'BZ are then sentto stripping column'84, wherein-the absorbed isoparaffin' is stripped from the oil by s'team' introduced through line 85. The steam-isoparafiin overhead in line 86 is condensed in condenserill and sent to separator 89. "Water is removed from the bottom of separator89 through line 90. iRecoveredisobutane is removed through the separator '89 through line 9|;and recycled to the towers ll and'3l.

Various modifications may '-be made in the above described procedure. For example, where the gas streams in lines 21 and'SB from fractionating columns 26 and 65, respectively, contain more'than insignificantamounts of olefins, the

streams may be passed to olefin feed line IO-Jfor recycle through the system. "In such case,;the

light'gases contained in these streams will be removed from the system. along withthe major portion of the light gases contained in the orlgi nal gas feed throughline'Sl from absorber 15. This and other modifications Will be' readily'apparent to those skilled in the art.

The particular operating conditions ,for selective absorption-'alkylation of the propylene and absorption alkylation .of the ethylene may be varied fromthose given hereinabove. However, while the operating conditions for selectivevabsorption-alkylation of the propylene may be varied 'tl ey' are somewhat morecritica-l than the operating 'conditionsfor absorption-allgyla i arises from hefact that not only isthe propylenet'o-beselectively a orb d nd a k ted; bu a so f om. the neces sity for orrela ing t mpe at a d cata y t.

tion of the ethylene.

propylene ==are preferably" between about 35 v Temperatures to be "employed for selective absorption a-lkylation *of whathigher. equilibrium'a'bsorption. contact ma be between The mol ratio of isobutane.

3 containing from a few per cent of jolefin upto as I 7 and ism-F1, and for these temperatures the fol-f lowing minimum concentrations of 'aluminuin bromide in isobutane absorption menstruum, as

determined by thedisclosure of the above-men tioned copending' application, may be employed:

of A118 Isobutane Ab-- sorption Men- The concentrations given above are minimum concentrations. Higher concentrations may also be employed although the use of higher concentrations tends to be uneconomical. Pressures of 60 to 250 pounds per square inch absolute may be employed for selective absorption-alkylation of the propylene. In order to provide for most efiicient absorption and alkylation of the propylene, the rate of flow of the isobutane absorption menstruumi'shouldbe such that for each \Veight Per Cent rain. j

highas 50 or '60 per cent andis ofutility m light olefin stream. contaminated with consider able proportions'of methaneor hydrog'enor' both. 1 Pure'isoparafdn streams or a'single pure iso-' paraffin need not necessarily be employed as the absorption menstruum; "A stream -01 'isobutanef maybe employed, orfa'stream of isop'entane','or

a stream of mixed isobutane-isopentane is 'satisfactory. Normal parafiins may also be present; although, if present, provision should be made to' remove these normal parafiins in 'the fractiona tion -system a-s 'rapidly'as they areintroduce'd-in? $1 the make-up isoparamn absorption meris-truun' to prevent build-up of these components inth absorption-reaction system. -Sma1l amounts'jof heavier parafiins, i, e.,"fparah1ns or'isoparafiins 7 having six or -n1'ore carbon atomsmayalso be) present and'have the advantage of raising the average molecular} weight of gtheiabsorption menstruum,,-'thereby reducing its volatilization'.

'Alkylate product introduced with the recycle equilibrium absorption contact, or, as otherwise expressed, for each theoretical plate or equivalent theoretical transfer unit; a residence time of 0.5 to 2%) seconds, preferably 3 to 10 sec-'- V onds, is obtained. However, longer residence times may be employedif desired, but in such cases ethylene will begin to react alon with the propylene to more than a minor extent, thereby resulting in a decreased yield of ethylene alky-late in the second Yzone. Also, a ratio of isobutane absorption menstruum to feed gas should be employed such that there will beat least 4.0 mols of isobutane to each mol of propylene dissolved in the absorption menstruuin at each point in the absorption-alkylation reaction zone. The

number of equilibriunijabsorption contacts required wi-lldepend upon the size and type of i g, the ratio of'liquid to gas, the rate at f which the propylene reacts with'the isoparaffin under the reaction conditions employed, and the temperature and pressure employed, and may be readily determinedby those skilled in the art.

For absorption-alkylation of the ethylene,

temperatures of about 50 F. to 200 F., prefer: ably 65 F. to 150 F.,"maybe employed. The pressures to be employedare preferably higher than jthose employed for 'absorption -alkylation of propylene and maybe "from 200 to 400 pounds per square ineh'absolute or higher, for example, as high as 700 pounds per square inch absolute.

i The concentration of dissolved aluminum bromide in the isobutaneabsorption menstruum may i,

be from" 0.1 to 12.0 weight per cent, or'some The residence time of liquid per 1 an'd 30* minutes. 7 absorption menstruum to dissolved ethylene may be-as low as l to l. jThenumberof equilibrium contactsjto be employed are subject to the same considerations mentioned above in. connectionj with'propylene.

If desired, an alkylationpromoter such as hy-f .drogen'brornide may be: employedior absorptionalkylation ofboththe propyleneand the ethylene, 3

advantageous for absorption alkylation of the it but the use of a. promoter will usuallyhe most ethylene. v j

The p o essa dapted for-use with streams Methane 87. Ethylene 1 '10.

\ Propylene catalyst stream is one :source or suchfhe avier; hydrocarbon introduction. .Since these hea-v r hydrocarbons would tend'to undergo competing reactions with the olefin in the presence of the catalyst; however, their? concentration shouldbe low; less' than 20 ,m-ol per centypreferably less j' than 10 mol per cent; and in all casesless' than of isoparaffin, pref one-half the molar quantity er'ably considerably less.

' As hereinbefore mentioned, the processmay be carried out i a-singletowerybut it is preferredij" to use two towers in order to obtainithe'benefitsjf of operating the second tower at a higher pressure than the first tower. Nevertheless,1satisfacferent. rates inorder to obtain thejd'esired iso parafiln -olefinratio in the zone where the .pro 'pylene is reacted and in' the, ziz'mewhere the? ethylene is reacted. 1 Further, the; temperature and the concentration of eataly-stin the absorpj tion menstruum may be varied in: bothi'zonesforl most emcient absorption-alkylation'.

The following example will'illustrat'e the sults to be obtainedfroin the processi of the .inventionz 1 A gas ofthe following composition 'wa spassed upwardly through a tower constructed of sixteen acked with five-eighthsj..

feet of six-inch pipe p inch Raschig rings:

e Component Isobutarie at F; cbmtmmgi 0.8 weight, 5 e r cent of dissolved aluminum bromidewas passed downwardly through the tower. The molfratio of isobutane entering the tower tolean gas leav ing the; tower was 0.5,j and the pressure within the tower was 'maintained at'i poundsyper'l square inchabsolute. .i in passing through-lathe packed/section, 133% of: the propylene was r moved, whilef less. than 2%. oftthe iethyleneewa removed; Thus,-, the 'iolefinr content of thegal mutt f 2 cen -H Peon- 9 leaving .the tower consisted of 1.0.44 volumes of ethylene to 0.35 volume of propylene or a ratio .of ethylene to propylene of 29 to 1, as compared with a ratio of V to 1 in the feed gas. An even larger proportion of the propylene could be re;- moved by the use of a tower containing a greater length of packing. Alkyla-tion-absorption of the gas leaving the packed tower in a bubble-plate column produced an isobutane-ethylene alkylate product consisting largely of 2,3 dimethyl butane and, because of the small quantity of propylene passing through said absorption column countercurrently to said gaseous stream a homogeneous, single phase stream of absorption oil consisting essentially of liquid isoparaffin hydrocarbons of not more than five carbon atoms and containing dissolved aluminum bromide in .a concentration of between about 0.2 and 4.2 weight per cent in quantity such that the mol ratio of isoparaifin absorption oil to dissolved propylene will be at least 40, maintaining a temperature between 35 F. and 150 F. and a pressure between 60 and 250 pounds per square inch absolute in said column, removing from said column a stream of rich absorption oil containng alkylate product of said isoparafiinabsorption oil and propylene,

passing the lean gaseous effluent from said column to a second absorption column, passing through said second absorption wcolumn countercurrently to the stream of said gaseous effluent a homogeneous, single phase stream of absorption oil consisting essentially of liquid isoparaiiin hydrocarbons of not more than five carbon atoms and containing dissolved aluminum bromide in a concentration of between about 0,1 and 12.0 weight per cent in quantity such that the mol, ratio of isoparatfinabsorption oil to dissolved ethylene will be at least 1, maintaining a temperature between .50 F. and 200 F. and a pressure between 200 and 700 pounds persquare inch absolute in said second column, removing from said column a stream of rich absorption oil containing alkylateproduct of said isoparafiin absorption oil and ethylene, separating aluminum bromide, absorption oil, and alkylate product from each of said rich absorption oils, dissolving said aluminum bromide in said absorption oi l and'rec-ycling co-said absorpa tion columns, separately recovering said separated alkylate products, passing gaseous overhead from said second absorption column through a third absorption column countercurrently to an essentially para-filn hydrocarbon oil having an average molecular weight considerablyin excess of that of the absorption oil employed in said first and second columns, stripping absorbed isoparafiin absorption oil from rich liquid absorption oil eflluent from said third absorption column, andre-- cycling stripped isoparafiinabsorption oil to said first and second absorption columns.

2. A process for the recovery and utilization of propylene and ethylene contained in a gaseous stream of light hydrocarbons which comprises '10 passing said stream into a packed absorption column, passing through said absorption column countercurrently to said gaseous stream a homogeneous-single phase stream of absorption oil consisting essentially of liquid isobutane and containing dissolved aluminum bromide in a concentration of between about 0.2 .and 4.2 weight per cent in quantity such that the mol ratioof isobutane absorption oil to dissolved propylene will be at least 40, maintaining a temperature between 35 and 150 F. and a pressure between 60 and 250 pounds per square inch absolute in said column, removing from said column a stream of rich absorption oil containing alkylate product of said isobutane absorption oil and propylene consisting'essentially of heptanes, passing lean gaseous efiluent from said column to a bubble plate column, passing through said bubblev plate column countercurrently to said stream of gase ous 'efiluent a homogeneous, single phase stream of absorption oil consisting essentially of liquid isobutane and containing dissolve-d aluminum bromide in a concentration of between about 0.1 and 12 weight per cent in quantity such that the mol ratio of isobutane absorption oil to dissolved ethylene will be at least 1, maintaininga temperature between 50 F. and 200 If. and a pressure between 200 and 700 pounds per square inch absolute in said column, removing fromsaid column a stream of rich absorption oil containing alkylate product of said isobutane-absorption oil and ethylene consisting essentially of 2,3-dimethylbutane, separating aluminum bromide, absorption oil, and alkylate product from each of said rich absorption oils, dissolving said aluminum bromide in said absorptionoil and recycling to said packed column and bubble plate column, separately recovering said; separated alkylate products, passing gaseous overhead from said bubble plate column through an absorption column countercurrently to an essentially parafiin hydrocarbon oil having an average-molecular weight considerably in eXCeSs of that of isobutane, stripping absorbed isobutane from rich liquid absorption oil effluent from said absorption column,-and recycling stripped isobutane to said packed column and said bubble plate column.

3; A process for the recovery and utilization of propylene and ethylene contained .in a gaseous streamof light hydrocarbons whichcomprises passing saidstream intoa first absorption column, passing through said absorption column countercurrently to said gaseous stream-a homogeneous, single phase stream of absorption oil consisting essentially of liquid isoparafii-n hydrocarbons of not more than five ,carbonatoms'and containing dissolved aluminum bromide i-n-a concentration of between about 0.2 and- 4.2 weight per cent in quantity such that the mol ratio of isoparaffin absorption oil to dissolved propylene will; be at leastr40, maintaininga' temperature between 35F. and F. and a pressure between 60 and 250 pounds per square inch absolute in said column, removing from said column a stream of rich absorption oi-lcontaining alkylate product of said isoparaffin absorption oil. and propylene, passing the lean gaseous eifluentr-fromsaidcolumn to a second absorption column, passing: through said second absorption column, countercurrently tothe stream of said gaseous eflluent-a-homogeneous, single phase stream of absorption oil consisting" essentially of liquid isoparafiin hydrocarbons of not more than five carbon atoms and containing dissolvedaluminum bromide in a concentration of between about 0.1 and 12.0 Weight isoparaffin absorption oil to dissolved ethylene will be at least 1, maintaining a temperature'between,50 F. and 200 F. and a pressure between T12 p o 5. A process for the recovery and utilization of propylene and ethylene contained in a gaseous stream of light hydrocarbons which'comprises passing said stream into a packed absorptioncol- 2'00and 700 pounds per square inch absolute in 5 passing through Said s p io Col n said second column, removing from said column countercurrently to said gase s eam a homoa stream of rich absorption oil containing alkylate geneous single phase stream of absorption oil product of said isoparaflin absorption oil and sti se t f l q idi paraffi y ethylene, separately recovering said alkylate prodb s of not more than five carbon atoms and ucts from said rich absorption oils, passing gas containing dissolved aluminum bromide in a conj e us' rh d from id second absorption p centration of between about 0.2 and 4.2 weight ems through a third absorption column counter- P Cent in q i y su h th tthe mol ratio of currently totan essentially araffin hydrocarbon isoperaffin a s t no l to s lv d pr py n oil having an average molecular weight considerwill be. at least 40, main a e p t e ably in excess of that of the absorptionoil em- 5 between 35 F. and 150 F. and apressure between ployed in said first and second columns, stripping 60 nd 50 pounds 'per sq a nc abs lute in ab rb d i amfli absorption 11 from r h said column, removing from said column a stream liquid absorption oil effluent from said third abf h s rp ion oil containing alkylat r u 'sorption column, and recycling stripped isoparof Said p r fi n'a s rption oil and propylene,

affin absorption oil tosaid firstand second absorp- 2o removing l n as us efflu t fr m said packed ti 1 V 5 column, removing from said lean gaseous efliuent 4Q A processfor the recovery and utilization of vaporized isoparaffin absorption oil, recycling said prdpylefle a t j cbntained gaseous removed isoparaflin absorption'oil tosaid packed f stream of light hydrocarbons which comprises absorptionrcolumn, pa s d l an s us ef- "passing said stream into afirst absorption column, fluent to a bubble p t eolumlo, passing. throu h a ng through i b pt d commn t said bubble plate column countercurrently to said icjurrently to said gaseous stream a homogeneous, Stream of gaseous emuento homogeneous, Single 0 I single phase stream of absorption oil consisting ha Stream of absorption. l C s sting essenessentially of liquidisoparafiin hydrocarbons of ially of liquid isoparafi n hydrocarbons f not t morerthan five b n atoms and o ta n more than five carbon atomsand containing disdig aluminum f m in a Concentration solved aluminum bromide in a concentration of of between about 0.2 and 42 weight per cent in between about andlZ Weightloer Cent in qu 'u jt ty' t t t m m, g am t1ty such that themol ratiov of isoparaffin absorpabsorption oil to dis'solved propylene will be at tion oil to dissolved t e w be t least 1.

least 40,-maintaining a temperature between 36 maintaining a p t e between 50 F. and. E and F! and a'messure between 60 m 250 200 F. and a pressure between 200 and 700 pounds pounds per square inch absolute in said column, per square inc i said bubble plate lu eremoving from said column'a stream of richabmoving from said columns a stream 10f rich orptiori' n containing'jalk'ylate product of said ,Sorptionoil containing a ate product of said lsoparafiln absorption oil and propylene, passing 40 fsoparomn absorption Oil and ethylene; Sepamb ;t h' lo g e em t from Saidc01um n to a mg aluminum bromidarabsorption oil, and alkyll-srfidabsorpfibn'Qommn pa through Said ate product'from said richabso'rptionoils, sepasecond absorption column countercurrently to Tate]? recovering Said. Separated alkylate P the stream of said gaseous effluent a homogeneous 9 dissolving Said: aluminum bromido i S single p ase stream of absorptionj oil consisting absorption oil a re ycling to said p ed and sse ntially of liquid isoparafiln hydrocarbons of bubble plate c l passing, gaseous overhead not more than five carbon atoms and containing fmm solid bubble. plate Column through a thirddissolved laluminum bromide in 'a concentration lmosorlotion Column r e tly to an essen-o "1 pf between about 0.1 and 12. 0 weight per cent in tially parafi oca bon oil hav an ve e 1 quantity such that the mol ratio of isoparaflin molecular Weight-considerably i e the,

absorption on ,toldissolved ethylene will be at isopa-reffin absorption oil ed i id p cked least 1. maintaining a" temperature between 50? F. and bubble Plate columns, Stripping a d f a d 200 and pr u e b t e 20 5 57 paraifin absorption oil from rich'liquid absorption ou d g inch l t said e'o oil effluent from said third absorption column, column; removing fromsaid column'a stream of and recycling strippediisopammn absorption Oil rich absorptio "oil pdntaining y t product to said packed and bubble plate columns. V

A oi id sop fiin absorption oil and ethylene, CHARLES OVID BAKER.

removing aluminum bromide as a concentrate separatelyfrom each of said rich absorption oils, REFERENCES D- separately recovering said alkylateproducts from 0 The following references are of record in the H tsjaid rich absorption oils, dissolving said aluminum file of this patent? i V a :4

romide concentrate in'the remainder of'theabo 7 sorption oils andrecycling to said absorption cola UNITED STATES PATENTS umnspajssing gaseous overhead from said second umber Name 7 t 3 Date 7 absorption column through a third absorption 65 2,312,539 Frey Mar. 2, 1943 column countercurrently to an essentially paraffin ,37 f SchlllZe J1me 1945 1 hydrgg rbo on having an average molecular 2,415,717 Watkins et a1. Feb. '11, 1947 j weig considerably in excess of that of the ab- Y 1 sorption oil employed in said first and second o i FOREIGN PATENTS j"" u l fi 's, stripping absorbed isoparaflin' absorp- .70 Number t y Date I tlon oil from rich liquid absorption oil effluent 496,273 Great 1938 1 from said third absorption column, and recycling *stripped isoparafiin absorption oil to said first and second absorption columns. 

